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Intro to Environmental Engineering > Midterm #2 > Flashcards

Midterm #2 Flashcards

1
Q

Issues with spatial distribution of water

A

Americas have higher water than people, opposite in Europe, Africa, and Asia. Oceania has little of both. Increasing demand for water in cities, especially in the Mountain West requires transport over greater distances and causes water conflicts between urban population centers and rural agricultural centers

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2
Q

Assumed water usage and WW production for a typical American

A

100 gal/day

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3
Q

Nutrients (water pollutant)

A

Sources: fertilizer, municipal wastewater, runoff, detergents. Effects: eutrophication, brown & slimy waters

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4
Q

Pathogens (water pollutant)

A

Sources: un- or poorly- treated sewage, CSOs. Effects: disease (cholera, diarrhea) and/or death

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5
Q

Toxic organics/emerging contaminants (water pollutant)

A

Sources: pesticides, herbicides, pharmaceuticals, sunscreen and other personal care products, endocrine disruptors. Effects: poisoning of humans and other species, disrupt metabolism and reproduction

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6
Q

Oxygen-depleting substances (water pollutant)

A

Sources: organic matter (BOD), municipal WW. Effects: fish death

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7
Q

Toxic metals (water pollutant)

A

Sources: Industrial discharge, mine tailings. Effects: poisoning of humans and other species

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8
Q

Suspended solids (water pollutant)

A

Sources: Soil erosion, industrial processes. Effects: murkiness, clogging of bed

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9
Q

Acid rain

A

Sources: contaminants due to power plants. Effects: acidification, human & ecosystem health impacts, damage to monuments

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10
Q

Point source pollution

A

Pollution that comes from a distinct source and be tracked and regulated easily

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11
Q

Nonpoint source pollution

A

Diffuse pollution that comes from many smaller sources and is harder to track and regulate

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12
Q

BOD

A

A measure of the potential for oxygen depletion from a pollutant; the amount of O2 needed to decompose organic matter

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13
Q

BOD5

A

5-day BOD measured after 5 days in a BOD bottle. = (DOi - DOf) / dilution factor

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14
Q

uBOD/L0

A

Maximum amount of O2 required to consume all organic matter in a sample after an infinite amount of time

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15
Q

CBOD

A

Amount of O2 required to decompose all carbon-containing OM

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16
Q

NBOD

A

Amount of O2 required to decompose all nitrogen-containing OM

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17
Q

ThOD

A

CBOD + NBOD

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18
Q

BODt

A

(DOi - DOt)/dilution factor

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19
Q

BODt

A

L0(1-e^-kt)

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20
Q

L0

A

BODt + Lt

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21
Q

kT

A

k20 * (theta^T-20)

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22
Q

BOD lab procedure

A

Add a mixture of nutrients, distilled water, and bacteria to two 2 BOD bottles, then add a WW sample to one such that the total volume of liquid in each bottle is the same. Store them in darkness at 20 C for 5 days and measure the DO before and after.

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23
Q

Processes in a water body after an oxygen demanding discharge

A

Decomposition of OM > reaeration and DO decreases until tc is reached. After reaching the critical point, reaeration > decomposition of OM and DO increases once more

24
Q

Effect of temp, L0

A

Increasing temp increases kD, so the D > R section of the curve gets steeper, tc wil occur sooner, and R > D section gets elongated. Higher L0 means tc will occur later and D > R section will become longer

25
Q

Physical, chemical, and biological constituents in untreated water

A

Turbidity, particles (including SS and OM), color, taste, odor, temperature, inorganic constituents (major & minor), natural and anthropogenic organics, organisms (bacteria, algae, viruses, protozoan), radionuclides (radon, uranium)

26
Q

Processes removing turbidity and particles

A

Coagulation/flocculation, sedimentation, granular filtration

27
Q

Processes removing major dissolved inorganics

A

Softening, aeration, membranes

28
Q

Processes removing minor dissolved inorganics

A

Membranes

29
Q

Processes removing pathogens

A

Sedimentation, filtration, disinfection

30
Q

Processes removing major dissolved organics

A

Membranes, adsorption

31
Q

MCLG

A

Maximim contaminant level below which there is no known or expected health risk. Non-enforceable

32
Q

MCL

A

Maximum contaminant level allowed in drinking water. Set as close to MCLG as possible. Enforceable

33
Q

Sedimentation

A

Clarifiers/sediment basins. Slow flow of water promotes sedimentation & removal of SS by gravity

34
Q

Coagulation/flocculation

A

Chemical addition neutralizes charges on particles, then gentle stirring of water causes particles to clump together into flocs. Removes particles that would not otherwise settle

35
Q

Filtration

A

Water is run through media in which small particles are trapped. Requires backwashing from time to time

36
Q

Disinfection

A

Addition of Cl (free or chloramines), O3, heat, or UV to kill pathogens, bacteria, & viruses. Primary vs. residual (secondary)

37
Q

Settling velocity

A

Calculated by Stokes’ law; velocity above which particles will not completely settle

38
Q

Critical velocity

A

vc = Q / H. Determines which particles will settle in a given basin based on physical system parameters. Vs > Vc will be removed completely

39
Q

Vs > Vc

A

100% efficiency

40
Q

Vs < Vc

A

efficiency = (Vs / Vc) * 100%

41
Q

Coagulant dose

A

Coagulant dose can be estimated from batch lab test results for optimum dose, flow rate, and reduction level needed

42
Q

Filtration rate

A

Q / Af (filter sizing - area)

43
Q

Free chlorine advantages and disadvantages

A

Adv: strong, effective against most microbes, simple maintenance and operation, inexpensive. Disadv: hazardous to store, sensitive to water quality, potential for harmful byproduct (DBPs) - react with to NOM to form carcinogens

44
Q

Chloramines advantages and disadvantages

A

Adv: less toxic and hazardous, no DBP, stable in distr. system (good residual). Disadv: not good against viruses, protozoan cysts, and bacterial spores

45
Q

UV advantages and disadvantages

A

Adv: very effective against bacteria, fungi, and protozoa; independent of water quality; no DBPs. Disadv: no residual effect, not very effective against viruses, expensive

46
Q

O3 advantages and disadvantages

A

Adv: effective against all types of bacteria. Disadv: expensive and complex, sensitive to water quality, forms DBPs with Br, no residual effect

47
Q

Primary disinfection

A

In plant, results in clearer effluent

48
Q

Residual disinfection

A

Pre-loading to overcome any contamination along the distribution line

49
Q

Effect of pH on chlorination

A

Cl2 –> HOCl. HOCl <–> OCl- and H+. pKa = 7.5 ideal (HOCl is stronger than OCl-). HOCl favored more by lower pH

50
Q

Log reduction method

A

Common quantification of pathogen removal. 1 log = 1/10, 2 log = 1/100, 3 log = 1/1000

51
Q

Ct

A

Product of concentration and time. Determines effect of pathogen removal technologies

52
Q

Physical, chemical, and biological constituents in municipal WW

A

BOD, SS, pathogens (TC), nutrients (TN & TP), toxics, and emerging materials

53
Q

Processes removing BOD

A

primary and secondary sedimentation, biological reactor

54
Q

Processes removing SS

A

primary and secondary sedimentation

55
Q

Processes removing pathogens

A

Primary sedimentation, disinfection, biological reactor

56
Q

Processes removing nutrients

A

Sedimentation, biological reactor, chemical precipitation

57
Q

Processes removing toxic chemicals

A

Sedimentation, biological rector, and advanced oxidative tech

Intro to Environmental Engineering (2 decks)

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